Surgical retention port and method of use

ABSTRACT

A surgical retention port particularly useful as an arthroscopic port for shoulder surgery is provided. The surgical retention port has a long pointed instrument such as a trocar or obturator, an inner cannula extending around the pointed instrument, a plurality of rotatable fingers coupled to the inner cannula, and an outer cannula extending around the inner cannula. In one embodiment of the invention, the inner cannula and long pointed instrument are keyed such that rotation of the long pointed instrument can effect rotational movement of the inner cannula. Rotation of the inner cannula in turn causes the rotation of the fingers from a first position where the fingers assume a collapsed configuration to a second position where the fingers assume an extended or open configuration.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a 371 national stage entry claiming priority fromPCT application no. PCT/US10/21339, with an international filing date ofJan. 19, 2010, which claims benefit from U.S. provisional applicationSer. No. 61/155,318, filed Feb. 25, 2009.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates broadly to surgical instruments and methods. Moreparticularly, this invention relates to a surgical retention port andits method of use and is particularly suited for arthroscopic surgeryand even more particularly suited for arthroscopic shoulder surgery,although it is not limited thereto.

2. State of the Art

Arthroscopy is a minimally invasive surgical procedure used to survey orrepair the interior of a joint or surrounding structures. Arthroscopy isconducted by inserting an arthroscope (endoscope) into the joint througha small incision and one or more arthroscopic tools through one or moreadditional incisions. Irrigation fluid is pumped into the joint in orderto distend the joint. Often, a trocar port device is used to make ordilate the incision and provide a port. The trocar port typicallyincludes a pointed instrument (trocar or obturator) and a cannula (port)extending around the trocar or obturator. The trocar or obturator isused to incise and/or expand an incision so that the cannula can bepushed into the incision. Then, the trocar or obturator can be removedfrom the cannula with the cannula remaining in the incision and actingas a port through which an arthroscopic instrument can be inserted. Thecannula of the trocar port device is often provided with a valve toprevent the escape of irrigation fluid from the surgical space.

In order to minimize trauma, sometimes it is desirable to anchor thecannula in place in the incision. In these situations it is known toprovide a retaining mechanism on the cannula. Examples of such retainingmechanisms in various laparoscopic arts include U.S. Pat. No. 3,397,699to Kohl (relating to a retaining catheter), U.S. Pat. No. 5,002,557 toHasson (relating to a retaining cannula utilizing a balloon), U.S. Pat.No. 5,203,773 to Green (relating to a tissue gripper for use with acannula), U.S. Pat. No. 6,589,214 to McGuckin, Jr. et al. (relating to avascular introducer sheath with a retainer). Unfortunately, none of theretaining cannulae known in the art have been particularly effectivewith respect to arthroscopic surgery. The joint space is relativelysmall when compared to other larger body cavites such as the thoracic orabdominal cavity. The field of view is thus relatively small and can befurther compromised by surrounding bony, tendinous, ligamentous andsynovial anatomic structures. These structures with an already limitedfield of view can further confound effective deployment of known orexisting retaining cannulae.

SUMMARY OF THE INVENTION

The present invention provides a surgical retention port. According toone aspect of the invention, the surgical retention port is particularlyuseful as an arthroscopic port for shoulder surgery.

According to another aspect of the invention, the surgical retentionport has a long pointed instrument such as a trocar or obturator, aninner cannula extending around the pointed instrument, a plurality ofrotatable fingers coupled to the inner cannula, and an outer cannulaextending around the inner cannula. According to one embodiment of theinvention, the inner cannula and long pointed instrument are keyed suchthat rotation of the long pointed instrument can effect rotationalmovement of the inner cannula. Rotation of the inner cannula in turncauses the rotation of the fingers from a first position where thefingers assume a collapsed configuration to a second position where thefingers assume an extended or open configuration.

According to one embodiment of the invention, the pointed instrumentincludes a shaft, a distal tip capable of dilating an incision, aproximal handle, and a mechanism for engaging with the inner cannula sothat rotation of the pointed instrument can result in rotation of theinner cannula. The pointed instrument is longitudinally movable relativeto the inner cannula and can be withdrawn completely from the inner andouter cannulas. The inner cannula includes a mechanism for engaging withthe mechanism of the pointed instrument. The rotatable fingers arecoupled to the inner cannula at a distal end thereof and can rotateabout pivots on the inner cannula. The hollow outer cannula has a handleat its proximal end including a seal, and a distal end having aplurality of windows with a plurality of longitudinally extending barsbetween the windows. In a collapsed configuration, the rotatable fingersassume a collapsed arrangement so that they are contained within theplurality of windows and preferably within a periphery of the outercannula. In an extended or open configuration, the fingers rotate andextend radially through the windows and beyond the periphery of theouter cannula in a manner substantially perpendicular to thelongitudinal axis of the port.

Objects and advantages of the invention will become apparent to thoseskilled in the art upon reference to the detailed description taken inconjunction with the provided figures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 a is an exploded perspective view of a first embodiment of asurgical retention port.

FIG. 1 b is a rear perspective view of the surgical retention port ofFIG. 1 a in a closed position.

FIG. 1 c is a rear perspective view of the surgical retention port ofFIG. 1 a in an open position.

FIG. 1 d is a front perspective view of the surgical retention port ofFIG. 1 a in an open position.

FIG. 2 a is a side view of the surgical retention port of FIG. 1 a in aclosed position.

FIG. 2 b is a side view of the surgical retention port of FIG. 1 a in anopen position.

FIG. 3 a is a cross-sectional view along line A-A of FIG. 2 a.

FIG. 3 b is a cross-sectional view along line C-C of FIG. 2 b.

FIG. 4 a is a rear view of the surgical retention port of FIG. 1 a inthe closed position seen from line B-B of FIG. 2 a.

FIG. 4 b is a rear view of the surgical retention port of FIG. 1 a inthe open position seen from line D-D of FIG. 2 b.

FIG. 5 is a cross sectional view along line E-E of FIG. 2 a.

FIG. 6 is a cross-sectional view along line H-H of FIG. 2 a.

FIG. 7 is a cross-sectional view along line I-I of FIG. 2 a.

FIG. 8 is an exploded perspective view of a second embodiment of asurgical retention port.

FIG. 9 is a side view of the second embodiment of FIG. 8 in an openposition.

FIG. 9 a is a cross sectional along line A-A of FIG. 9.

FIG. 9 b is a view taken along line D-D of FIG. 9.

FIG. 9 c is a similar view of FIG. 9 b but with the fingers of thesurgical retention port in an open position.

FIG. 10 is a side view of the obturator and inner cannula of the secondembodiment and without the outer cannula except for a portion of the pinof the outer cannula.

FIG. 10 a is an enlarged view of a locking slot area of the innercannula of the second embodiment.

FIG. 11 a is a side view of an elastomeric sleeve which may be used inconjunction with the first and second embodiments of the surgicalretention port.

FIG. 11 b is a side view of the elastomeric sleeve of FIG. 11 a shown ina tenting position.

FIG. 12 a is a cross-sectional view of another embodiment of theinvention in a closed position.

FIG. 12 b is a cross-sectional view of the embodiment of FIG. 12 a in anopen position.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Turning now to FIGS. 1 a-1 d, a first presently preferred embodiment ofa surgical retention port of the invention is seen. The surgicalretention port 10 of FIGS. 1 a-1 d broadly includes a long pointedinstrument (trocar or obturator) assembly 20, an inner cannula 30, anouter cannula assembly 40, rotatable fingers 50 a-50 d (three shown inFIG. 1 a) which are coupled by pins 60 a-60 d to the inner cannula 30,and an optional locking collar 70. At least one o-ring 80 is preferablyprovided as will be described hereinafter.

As seen in FIGS. 1 a and 5, the long pointed instrument assembly 20includes a proximal handle 22, a shaft 24 defining a longitudinal axis xand having a rib, key or other interface mechanism 25 for rotating theinner cannula 30 (as described in more detail hereinafter), and apointed distal tip 26 which is preferably capable of dilating anincision. In the first embodiment, the pointed instrument assembly is anobturator assembly as the pointed tip includes a rounded end 27 does nothave any sharp edges. However, if desired, the pointed tip could havesharp edges and function as a trocar. As seen in FIGS. 1 a-1 d, 2 a, 2b, 4 a and 4 b, the proximal handle 22 has longitudinal cut-outs orgrooves 28 which aid in gripping the handle as well as helping toprovide a mechanism for determining whether the port 10 is in an open orclosed position (as will be described in more detail hereinafter).

As seen in FIGS. 1 a and 5, the hollow inner cannula 30 extends aboutthe long pointed instrument 20 in a manner which permits the longpointed instrument 20 to be movable longitudinally relative to saidinner cannula 30. Thus, by gripping the handle 22 and moving it distallyand proximally, the shaft 24 of the long pointed instrument 20 can beinserted into and through the cannula 30 and can be removed completelyfrom the inner cannula 30. The inner cannula 30 has at its proximal end31 at least one groove, slot or keyway (i.e., a second interfacemechanism) 32 which is designed to receive the rib or key interface 25of the shaft 24 of the long pointed instrument 20. In the preferredembodiment, four such keyways are provided at ninety degree rotationsabout the proximal end 31 of the inner cannula 30. When the rib or keyof shaft 24 is engaged in a keyway 32 of the inner cannula, rotation ofthe long pointed instrument 20 about the long axis x causes rotation ofthe hollow inner cannula 30. In addition, the inner cannula 30 has adistal end 33 which defines four longitudinal holes 34 a-34 d (two shownin FIG. 5) which receive pins 60 a-60 d. As will be described in moredetail hereinafter, and as seen in FIGS. 1 a, 3 a, 3 b and 5, the verydistal end of said hollow inner cannula comprises a tapered distal ring35 coupled to a more proximal portion 36 of the distal end 33 of thehollow inner cannula 30 by a plurality of links 37. In the firstembodiment, the links 37 each have a first portion 37 a having athickness substantially equal to the thickness of the hollow innercannula 30 and a second radially extending portion 37 b having athickness less than the thickness of the hollow inner cannula 30. Theradially extending portions 37 b prevent the distal ends of hookedinstruments which may be inserted into the port from getting caught inthe distal end of the inner cannula 30. The links 37 define a pluralityof gaps 38 in which at least a portion of the fingers 50 are located, aswill be described in more detail hereinafter. The pins 60 a-60 d extendfrom the longitudinal holes 34 a-34 d in the distal ring 35 through thegaps 38 (and fingers 50) and into the holes 34 a-34 d in the moreproximal portion 36 of the distal end of cannula 30. Proximal of thedistal end 33 of the inner cannula 30 and distal the proximal end 31,the inner cannula 30 has at least one groove 39 (two shown in FIG. 5) inits outer surface for receiving an o-ring 80. The o-ring(s) seat(s) inthe groove 39 and serve(s) the dual functions of providing friction torotational movement of the inner cannula 30 relative to the outercannula 40, and preventing fluid from exiting the surgical site throughany gaps between the cannulas. The groove 39 may be circular, or, asdescribed hereinafter with respect to the embodiment of FIGS. 12 a and12 b may be oval to serve a locking function.

Details of the outer cannula 40 are best seen in FIGS. 1 a, 3 a, 3 b,and 5. The outer cannula 40 includes an elongate portion 41, a proximalend 42 which houses a valve assembly 81 (discussed in more detailhereinafter), and a distal end 43. At least a part of the elongateportion 41 of the cannula preferably has a slightly oval cross-sectionas described hereinafter with reference to FIG. 6. In fact, as describedhereinafter with respect to the embodiment of FIGS. 12 a and 12 b, boththe inner and outer surfaces of outer cannula 40 may include portionswhich are oval. The distal end 43 of the outer cannula 40 includes atapered ring 44 coupled to the remainder of the distal end by aplurality of longitudinal bars 45 which define windows 46. The bars havetwo lateral faces 47, 48 which act as camming surfaces for the fingers50 such that rotation of the inner cannula 30 in a first rotationaldirection relative to said outer cannula 40 causes the fingers to engageone face (e.g., 47), and rotation of the inner cannula in the oppositedirection causes the fingers to engage the other face (e.g., 48), asdescribed in more detail below.

As previously mentioned, fingers 50 a-50 d are coupled to the innercannula 30 by pins 60 a-60 d. As seen best in FIGS. 3 a and 3 b, each ofthe fingers 50 a-50 d has an integral pivot portion 52 which rotatesabout the pins and an extending portion 54 which extends radiallyoutwardly in an “open” position (FIG. 3 b). More particularly, incross-section, each finger 50 takes the general form of a shoe footprintwith the heel being the pivot portion 52, and the sole being theextending portion 54. As seen in FIGS. 3 a and 3 b, the pivot portions52 sit in the gap areas 38 of the distal end of the inner cannula 30,and the pivot portions 52 have a thickness or diameter substantiallyequal to the diameter of the inner cannula 30. Also, as seen in FIG. 3a, in a closed or collapsed configuration, the extending portions 54 ofthe feet sit in the gap areas 38 of the inner cannula 30 as well as inthe windows 46 of the outer cannula 40. In the collapsed configuration,the inside surface 55 of the extending portions 54 of the fingersengages or is adjacent the radially extending portions 37 b of the links37 of the distal end of the inner cannula 30, while an outside surface56 is substantially within the periphery (outer surface) of the outercannula 40. In a preferred embodiment, a portion of the outside surface56 is defined by a radius r equal to the radius of the outer surface ofthe outer cannula 40. In a second open or extended configuration seen inFIG. 3 b, the extending portions 54 of the fingers 50 extend radiallythrough the windows 46 in the outer cannula 40 and well beyond theperiphery in a manner substantially perpendicular to the longitudinalaxis x of the pointed instrument 20. In a preferred embodiment, thediameter of the instrument 10 defined by the open fingers from tip 57 totip 57 is approximately sixty percent larger than the diameter of thedistal portion 43 of the outer cannula 40. The fingers 50 areconstructed to be substantially small in radial dimension when in theopen configuration, yet sufficiently large and stiff to support thecannula. The curvilinear shape of the fingers is adapted to keep thefingers confined to the cannula when in the closed configuration, yethave a surface area that would minimize trauma to the tissue when in theopen configuration. In a preferred embodiment the fingers are 0.25 inchin radial dimension and 0.10 inch in longitudinal thickness (a 5 to 2ratio of radial dimension to longitudinal thickness dimension) whichprovides the desired properties given the materials and shapes of thefingers.

With the inner cannula 30, outer cannula 40, and fingers 50 arranged asdescribed, it will be appreciated that with the fingers 50 in acollapsed configuration as in FIG. 3 a, upon rotation of the innercannula 40 counterclockwise (looking distally), the inside surfaces 55of the fingers 50 near their tips 57 will engage the camming surfaces orfaces 48 of first bars 45 of the outer cannula 40 such that the faces 48will force the fingers 50 to rotate about the pins 60 and extendradially outerwardly. Eventually, after about sixty to sixty-fivedegrees of counterclockwise rotation, and as suggested by FIG. 3 b, theoutside surfaces of the rotating portions 52 will engage an outer edgeof the thick portions 37 a of the links 37 such that rotation cannotcontinue. In the opposite direction, from the fully open position ofFIG. 3 b, rotation of the inner cannula 40 in a clockwise direction(looking distally) will not cause the fingers 50 to start closing untilthe outer surfaces 56 of the extending portions 54 of the fingers areengaged by the camming surfaces 47 of second bars 45 (which occurs afterabout fifty degrees of clockwise rotation from the fully open position).Continued clockwise rotation eventually causes the complete closing ofthe fingers 50 as shown in FIG. 3 a. Thus, for any given finger, one bar45 of the outer cannula 40 causes the finger to open, while a second bar45 which is located ninety degrees clockwise of the first bar causes thefinger to close.

As previously described, rotation of the inner cannula 30 relative tothe outer cannula 40 is obtained by rotation of the elongate pointedinstrument 20 relative to the outer cannula 40. In particular, aspreviously described, the rotation of instrument 20 causes engagement ofa projection, rib, or key 25 on the instrument 20 with a groove, slot,or keyway in the inner cannula 30. The rotation is typicallyaccomplished by a practitioner through gripping the handle 22 of theinstrument 20 in one hand, and the proximal end 42 of the outer cannula40 with the other hand and rotating one or the other.

Details of the proximal end 42 of the outer cannula 40 are seen in FIG.5. As previously mentioned, the proximal end 42 provides a housing for avalve assembly 81 which includes a polymeric flexible cross slit valve82 having a base 83 and a polymeric stretchable washer valve 84 whichengages the proximal side of the base 83 of the slit valve 82. Thehousing has an inner surface 42 a which defines an enlarged cavity 85 inwhich the valves 82 and 83 are located. Extending proximally from thehousing is an inner circumferential projection 86 as well as a proximalarm 87 which defines a plurality of holes 88 configured for receivingpins 89 of an end cap 90. As seen in FIG. 5, the circumferentialprojection 86 engages the proximal side of the base 83 of the slit valve82. The distal side of the washer valve 84 is engaged by a projection 91on the end cap 90. In this manner, the washer valve 84 and slit valve 82are held in place in the cavity 85 of the housing of the outer cannula40 when the pins 89 of the end cap 90 are force fit, glued, or otherwiseretained in the holes 88 of the proximal arm 87 of the outer cannula 40as seen in FIG. 7. The proximal end 42 can optionally be provided with aside port (not shown) which can be manually operated to reduce andrelieve pressure within the cavity 85. By relieving such pressure, bloodwithin the cavity can be removed and the field of view can thereby beimproved.

As seen in FIGS. 1 b and 4 a, the end cap 90 is preferably provided withvisible indicators 95 on its proximal surface near its circumference.When the pointed instrument assembly 20 is aligned with the innercannula 30 such that the fingers 50 are in a collapsed position, thegrooves 28 on the handle 22 are located such that indicators 95 can beseen by the practitioner. When the handle 22 is rotated in order tocause the inner cannula 30 to rotate and to cause the fingers 50 toopen, the grooves 28 on the handle 22 are rotated such that the view ofthe indicators 95 is obstructed (FIGS. 1 c and 4 b). Thus, thepractitioner can determine that the fingers 50 are at least partiallyextended.

As seen best in FIG. 5, the proximal side of the end cap 90 defines atapered entry or port 97. The tapered entry is useful for directingarthroscopic tools past the valves 84 and 82 and into and through theinner cannula 30 during use of the surgical retention port 10, as willbe described hereinafter.

According to one embodiment of the invention, the surgical retentionport 10 is provided with a locking collar 70. As seen in FIGS. 1 a-1 d,2 a, 2 b, 5 and 6, the locking collar 70 has a proximal scallopedportion 71 which is designed for being gripped and rotated easily by apractitioner, and a tapered distally extending nose portion 72 whichterminates in a flat ring 73. Ring 73 defines an oval-shaped opening 74.The oval-shaped opening 74 is similarly shaped to and slightly largerthan the previously described oval-shaped outer surface of the elongateportion 41 of the outer cannula 40. In this manner, when the largerdiameter opening of the ring 73 is aligned with the larger diameterouter surface of the elongate portion 41 of the outer cannula, thelocking collar 70 can be easily slid forward and backward along the saidouter cannula 40. When it is desired to lock the locking collar in placeon the outer cannula, the locking collar 70 can be rotated to causemisalignment of the larger diameter axes (i.e., the smaller diameteropening of the ring 73 will be rotated toward the larger diameter outersurface of the elongate portion 41 of cannula 40) such that the lockingcollar 70 will engage and interfere with the cannula 40 (seenschematically in FIGS. 5 and 6), and lock into place. Rotation back willrelease the locking collar 70 from the cannula 40. Preferably, thediameter of the ring 72 is similar to the diameter of the instrument 10defined by the open fingers 50 from tip 57 to tip 57. In this manner,when the fingers 50 are opened inside a patient's skin (e.g., adjacent ashoulder) and the locking collar 70 is slid down the cannula to engagethe outside of the patient's skin, a strong and stable situation isestablished with the surgical retention port 10 affixed in the patient.That is, when the locking collar is locked on the cannula, it providesboth longitudinal stability of the cannula within the patient andprovides pressure on the outside of the outer cannula to causesufficient interface between the inner and outer cannulas resulting inlocking of the fingers in the open configuration. When the long pointedinstrument assembly 20 is withdrawn from the inner cannula 30, slitvalve 82 closes to prevent fluid from exiting the surgical sight via theretention trocar port. A port for arthroscopic (or laparoscopic) tools(not shown) is thus established.

In use, the surgical retention port 10 with the long pointed instrument20, an inner cannula 30, an outer cannula assembly 40, rotatable fingers50 a-50 d in a collapsed position, and locking collar 70 is obtained.The retention trocar port 10 can be pushed into an incision (not shown)of a patient such that the tapered distal end 26 of the instrument 20,and then the tapered distal end 35 of the inner cannula 30 (whichextends past the distal end of the outer cannula 40—see FIG. 5), andthen the tapered distal end 43 of the outer cannula 40 dilate theincision so that at least the distal ends of the inner and outercannulas 30, 40 and fingers 50 are located inside the patient. Byholding the proximal housing 42 of the outer cannula 40 and the handle22 of the long pointed instrument, and rotating one relative to theother (e.g., rotating the handle 22 counterclockwise relative to theouter cannula 40), the fingers 50 coupled to the inner cannula 30 can bepushed into an extended position (FIG. 3 b). With the fingers 50 in theextended position, the locking collar (if available) can be sliddistally along the outer cannula until it engages the skin of thepatient, and then rotated to lock into place. The long pointedinstrument 20 can then be removed from the inner cannula and out throughvalves 82, 84 housed in the proximal housing of the outer cannula 40.Optionally, the long pointed instrument 20 can be removed before thelocking collar 70 is slid distally or before it is rotated to lock intoplace.

With the long pointed instrument 20 removed from the assembly, thedouble slit valve 82 acts to prevent fluid from escaping through theretention trocar port 10. When desired, arthroscopic or laparoscopicinstruments (not shown) can be inserted via the port 97 of the end cap90, and past the washer valve 84 and double slit valve 82 and throughthe inner cannula 30 and out the distal end thereof to the surgical site(not shown). Upon completion of the surgery, or upon desiring to removethe arthroscopic or laparoscopic instrument for any reason, thearthroscopic or laparoscopic instrument may be withdrawn back throughthe proximal end of the retention trocar port 10, with the double slitvalve 82 again acting to prevent fluid from exiting. The pointedinstrument 20 is then reinserted into the inner cannula 30 via port 97,washer valve 84 and slit valve 82 until the handle 22 stops against theend cap 90. The locking collar 70 (if used) can then be rotated tounlock it from the outer cannula 40 and slid proximally out ofengagement with the skin. With the pointed instrument 20 in place in theinner cannula 30, the handle 22 is rotated clockwise to cause the innercannula 30 to rotate clockwise and to force fingers 50 to close into thecollapsed position (FIG. 3 a). The entire retention trocar port assembly10 may then be removed from the surgical site.

A second embodiment of the invention is seen in FIGS. 8-10. The parts ofthe second embodiment which are the same or similar to the parts of thefirst embodiment are numbered with like numbers, except “100” higher.

The surgical retention port 110 of FIGS. 8-10 broadly includes a longpointed instrument (trocar or obturator) assembly 120, an inner cannula130, an outer cannula assembly 140, rotatable fingers 150 a-50 d whichare coupled by pins 160 a-160 d to the inner cannula 130, and anoptional locking collar 170. The long pointed instrument assembly 120includes a proximal handle 122, a shaft 124 defining a longitudinal axisx and having a rib, key or interface mechanism 125 for rotating theinner cannula 130 and a pointed distal tip 126. The proximal handle 122is different than handle 22 of the first embodiment and has discs 122 acoupled by fins 122 b. The discs are spaced so as to permit the fingersof the practitioner to easily grip and rotate the handle 122.

The hollow inner cannula 130 extends about the long pointed instrument120 in a manner which permits the long pointed instrument 120 to bemovable longitudinally relative to said inner cannula 130. Thus, bygripping the handle 122 and moving it distally and proximally, the shaft124 of the long pointed instrument 120 can be inserted into and throughthe cannula 130 and can be removed completely from the inner cannula130. The inner cannula 130 has at or near its proximal end 131 at leastone groove, slot or keyway (i.e., a second interface mechanism) 132which is designed to receive the rib or key interface 125 of the shaft124 of the long pointed instrument 20. In this manner, rotation of thelong pointed instrument 120 about the long axis x causes rotation of thehollow inner cannula 130. In addition, the inner cannula 130 has adistal end 133 which defines four longitudinal holes 134 a-134 d (oneshown in FIG. 8) which receive pins 160 a-160 d. The very distal end ofsaid hollow inner cannula comprises a tapered distal ring 135 coupled toa more proximal portion 136 of the distal end 133 of the hollow innercannula 130 by a plurality of links 137.

Unlike the links 37 of the first embodiment, links 137 of the secondembodiment are essentially bars having a thickness substantially equalto the thickness of the hollow inner cannula 30 and do not includeradially extending portions having a thickness less than the thicknessof the hollow inner cannula 130. The links 137 define a plurality ofgaps 138 in which at least a portion of the fingers 150 are located. Thepins 160 a-160 d extend from the longitudinal holes 134 a-134 d in thedistal ring 135 through the gaps 138 (and fingers 150) and into theholes 134 a-134 d in the more proximal portion 136 of the distal end ofcannula 130. Proximal of the distal end 133 of the inner cannula 130 anddistal the proximal end 131, the inner cannula 130 has at least onegroove 139 in its outer surface for receiving an o-ring 180. Theo-ring(s) seat(s) in the groove 139 and serve(s) the primary function ofpreventing fluid from exiting the surgical site through any gaps betweenthe cannulas 130 and 140.

Another difference between inner cannula 130 and the inner cannula 30 ofthe first embodiment is that inner cannula 130 defines a locking slot196 which is best seen in FIGS. 9 b, 9 c, and 10 a. Locking slot 196 iscut into (but preferably not through) the inner cannula 130, is locateddistal the keyways 132, and is arranged as a bayonet lock with twonarrowing areas 197 a, 197 b, through which a pin 149 of the outercannula (discussed below) can be forced. In this manner, the pin 149 canassume three different positions within the locking slot 196 (e.g., 198a, 198 b, 198 c) and prevent inadvertent rotation of the inner cannula130 relative to the outer cannula 140. When the pin 149 is in theposition 198 a shown in FIGS. 9 b and 10 a, the fingers 150 are in acollapsed position. When the inner cannula 130 is rotatedcounterclockwise relative to the outer cannula 140 such that pin 149 isforced through the first narrowing area 197 a, the fingers 150 assume apartially open position (not shown). When the inner cannula 130 isfurther rotated counterclockwise relative to the outer cannula 140 suchthat pin 149 is forced through the second narrowing area 197 b intoposition 198 c, the fingers 150 assume a completely open position asshown in FIG. 9 c. Alternatively the pin can be fixed relative to theinner cannula and forced through a locking slot in the outer cannula andto provide the same locking functionality.

Outer cannula 140 of the second embodiment includes an elongate portion141, a proximal end 142 which houses a valve assembly 180, and a distalend 143. The outer cannula 140 is substantially identical to the outercannula 40 of the first embodiment except that it includes thepreviously mentioned press fit pin 149 extending inwardly from theelongate portion 141 and located adjacent the locking slot 196 of theinner cannula 130. At least a part of the elongate portion 141 of thecannula has a slightly oval outer cross-section. The distal end 143 ofthe outer cannula 140 includes a tapered ring 144 coupled to theremainder of the distal end by a plurality of longitudinal bars 145which define windows 146. The bars have two lateral faces 147, 148 whichact as camming surfaces for the fingers 150 such that rotation of theinner cannula 130 in a first rotational direction relative to said outercannula 140 causes the fingers to engage one face (e.g., 147), androtation of the inner cannula in the opposite direction causes thefingers to engage the other face (e.g., 148).

Fingers 150 a-150 d are coupled to the inner cannula 130 by pins 160a-160 d. As seen best in FIG. 9 a, each of the fingers 150 a-150 d hasan integral pivot portion 152 which rotates about the pins and anextending portion 154 which extends radially outwardly in an “open”position. More particularly, in cross-section, each finger 150 takes thegeneral form of a shoe footprint with the heel being the pivot portion152, and the sole being the extending portion 154. The pivot portions152 sit in the gap areas 138 of the distal end of the inner cannula 130,and the pivot portions 152 have a thickness or diameter substantiallyequal to the diameter of the inner cannula 130. In a closed or collapsedconfiguration, the extending portions 154 sit in the gap areas 138 ofthe inner cannula 130 as well as in the windows 146 of the outer cannula140.

With the inner cannula 130, outer cannula 140, and fingers 150 arrangedas described, it will be appreciated that with the fingers 150 in acollapsed configuration, upon rotation of the inner cannula 140counterclockwise (looking distally), the inside surfaces 155 of thefingers 150 near their tips 157 will engage the camming surfaces orfaces 148 of first bars 145 such that the faces 148 will force thefingers 150 to rotate about the pins 160 and extend radiallyouterwardly. Eventually, the outside surfaces of the rotating portions152 will engage the links 137 such that rotation cannot continue. In theopposite direction, from the fully open position, rotation of the innercannula 140 in a clockwise direction will not cause the fingers 150 tostart closing until the outer surfaces 156 of the extending portions 154of the fingers are engaged by the camming surfaces 147 of second bars145. Continued clockwise rotation eventually causes the complete closingof the fingers 150. Thus, for any given finger, one bar 145 of the outercannula 140 causes the finger to open, while a second bar 145 which islocated ninety degrees clockwise of the first bar causes the finger toclose.

Rotation of the inner cannula 130 relative to the outer cannula 140 isobtained by engagement of a projection, rib, or key 125 on instrument120 with a keyway 132 of the inner cannula 130 (see FIG. 10), androtation of the elongate pointed instrument 120 relative to the outercannula 140. The rotation is typically accomplished by a practitionerthrough gripping the handle 122 of the instrument 120 in one hand, andthe proximal end 142 of the outer cannula 140 with the other hand androtating one or the other.

The proximal end 142 of the outer cannula 140 provides a housing for avalve assembly 180 which includes a polymeric flexible cross slit valve182 and a polymeric stretchable washer valve 184. The housing issubstantially identical to housing of the first embodiment and providesholes (not shown) for receiving pins 189 of end cap 190 which are forcefit, glued, or otherwise retained in the holes.

According to one embodiment of the invention, the surgical retentionport 110 is optionally provided with a locking collar 170. As seen inFIGS. 8 and 9, locking collar 170 is different than locking collar 70 ofthe first embodiment. More particularly, locking collar 170 is generallyfrustoconical in shape and tapers down in diameter as it extendsproximally. The locking collar 170 includes external ribs 171 which aredesigned for being gripped and rotated easily by a practitioner. As seenbest in FIG. 8, the locking collar 170 also includes an internal ring173 with radial fingers 175. The ring 173 defines an oval-shaped opening174. The oval-shaped opening 174 is similarly shaped to and slightlylarger than the oval-shaped outer surface of the elongate portion 141 ofthe outer cannula 140. In this manner, when the larger diameter openingof the ring 173 is aligned with the larger diameter outer surface of theelongate portion 141 of the outer cannula, the locking collar 170 can beeasily slid forward and backward along the outer cannula 140. When it isdesired to lock the locking collar in place on the outer cannula, thelocking collar 170 can be rotated to cause misalignment of the largerdiameter axes (i.e., the smaller diameter opening of the ring 173 willbe rotated toward the larger diameter outer surface of the elongateportion 141 of cannula 140) such that the locking collar 170 will engageand interfere with the cannula 140 and lock into place. Rotation backwill release the locking collar 170 from the cannula 140.

The surgical retention port 110 of the second embodiment is used insubstantially the same manner as the surgical retention port 10 of thefirst embodiment. The primary difference between the two is thatadditional resistance to rotation of the inner cannula 130 relative tothe outer cannula 140 (and thus the opening and closing of fingers 150)is generated by the bayonet locking mechanism; i.e., pin 149 and lockingslot 196 with narrowing areas 197 a, 197 b. Thus, in the secondembodiment, the system is actively locked by the bayonet locking system,whereas in the first embodiment the system is actively locked byoperation of the locking collar 70.

According to another embodiment of the invention, a highly flexibleelastomeric sleeve 200 seen in FIG. 11 a can be slid over the distal endof the outer cannula 40, 140 of either of the embodiments of theinvention. The ends 201, 202 of the elastomeric sleeve are preferablyfixed to the outer cannula by gluing, welding, or any other desiredtechnique. End 201 is preferably fixed distal of fingers 50, 150, whileend 202 is preferably fixed proximal of fingers 50, 150. Withelastomeric sleeve 200 fixed in place and extending over windows 46, 146of the outer cannula, when the fingers 50, 150 are opened, the fingers50, 150 will cause the elastomeric sleeve 200 to stretch and “tent” asshown in FIG. 11 b. In this manner enhanced anchoring may beaccomplished.

According to another embodiment of the invention, the inner cannula 30(130) outer cannula 40 (140) and o-ring 80 may be adapted such thatrotation of the inner cannula inside the outer cannula to open thefingers 50 (150) also provides significant friction which actively locksthe unit in the open position. Significant force may be used to overcomethe friction and move the fingers back into the closed position. Moreparticularly, FIGS. 12 a and 12 b are cross-sections taken through asurgical retention port at the location of an o-ring (e.g., o-ring 80)described above with reference to FIG. 5. As in the previousembodiments, an obturator 224, an inner cannula 230, and an outercannula 240 are shown. However, in the embodiment shown in FIGS. 12 aand 12 b the outer cannula 240 at the location of o-ring 280 has aninner surface 240 a which is oval (as well as oval outer surface 240 b),and the inner cannula 230 has an inner surface 230 a which is circularand an outer surface 230 b which is circular. As a result, at somepoints, the circular outer surface 230 b of inner cannula 230 iscontacting or nearly contacting the oval inner surface 240 a of outercannula 240, and at some points, there is gap between the two. Inaddition, the inner cannula 230 has a groove or race 239 which is ovalin shape (the groove being between the oval inner line shown as 239 andthe circular outer diameter 230 b of the inner cannula 230). Thus, thegroove 239 is deeper into the cannula 230 at some locations then atothers. The o-ring 280 always fills the groove 239 as well as any spaceor gap between the outer surface 230 b of the inner cannula 230 and theinner surface 240 a of the outer cannula. With this arrangement, whilethe o-ring is squeezed or compressed in the groove 239 and between theouter surface 230 b of the inner cannula 230 and the inner surface 240 aof the outer cannula around the entire circumference of o-ring, thecompression is relatively evenly distributed, with a maximum compressiondenoted in FIG. 12 a by the minimum o-ring thickness X1. This result isobtained because the oval groove 239 is deepest where the space betweenthe inner cannula and outer cannula is smallest (denoted by M), and theoval groove 239 is shallowest where the space between the inner cannulaand outer cannula is largest (denoted by P) such that the o-ring standssignificantly proud of the outer surface 230 b of the inner cannula 230.

When the obturator 224 is rotated to cause the inner cannula 230 torotate with respect to the outer cannula 240 (to open the fingers), theposition of the o-ring 280 in the oval groove 239 reaches the situationshown in FIG. 12 b. More particularly, as seen in FIG. 12 b, thelocation on the inner cannula 230 where the groove 239 is deepest is nowaligned with the location P where the space between the inner cannula230 and the outer cannula 240 is largest, and the location on the innercannula 230 where the groove 239 is shallowest is now aligned with thelocation where the space between the inner cannula 230 and outer cannula240 is smallest (M). At this rotational configuration, the o-ring 280 issqueezed to a thickness X2 which is significantly smaller than X1 andthe compression is not well distributed. The resulting forces tend tokeep the inner cannula 230 locked relative to the outer cannula 240 withthe fingers of the surgical retention port arranged in the open orextended position.

In the embodiment of FIGS. 12 a and 12 b, it desirable for the o-ring280 to be able to be significantly compressed. The hardness chosen forthe o-ring will generally depend upon the level of ovality of the groove290 and the ovality of the inner surface 240 a of the outer cannula 240.By way of example only, and not by way of limitation, o-ring 280 may bemade from a material having a hardness of approximately 80A Durometer.It will be appreciated that the arrangement of FIGS. 12 a and 12 b canbe used with either of the embodiments shown in FIGS. 1-7 and 8-10, withor without locking collar 70, 170, and with or without the bayonet lockarrangement of FIGS. 8-10.

There have been described and illustrated herein several embodiments ofa surgical retention port and methods of its use. While particularembodiments of the invention have been described, it is not intendedthat the invention be limited thereto, as it is intended that theinvention be as broad in scope as the art will allow and that thespecification be read likewise. Thus, while the use of four fingers hasbeen disclosed, it will be appreciated that different numbers of fingerscould be used as well. Further, while the fingers are shown coupled tothe cannula by a hinge constructed with a pivot pin, it is recognizedthat other pivot mechanisms including a living hinge constructionintegral with the cannula can be used. In addition, while a key andkeyway engagement mechanism for the pointed instrument and inner cannulahas been disclosed, it will be understood that other mechanisms can beused. It will therefore be appreciated by those skilled in the art thatyet other modifications could be made to the provided invention withoutdeviating from its spirit and scope as claimed.

What is claimed is:
 1. A surgical retention port, comprising: a longpointed instrument having a shaft defining a longitudinal axis, a distaltip capable of dilating an incision, a proximal handle, and an firstinterface mechanism; a hollow inner cannula extending about said longpointed instrument with said long pointed instrument movablelongitudinally relative to said inner cannula, said inner cannula havinga distal end and a second interface mechanism, said second interfacemechanism for engaging with said first interface mechanism of said longpointed instrument such that rotation of said long pointed instrumentcauses rotation of said hollow inner cannula; a plurality of radiallyextendible fingers coupled to said distal end of said hollow innercannula, each of said radially extendible fingers having a pivot portionand an extending portion and a pivot axis parallel said longitudinalaxis; and a hollow outer cannula having a proximal end, a distal enddefining a periphery and a plurality of windows, said distal endincluding a plurality of bars between said windows, wherein in a firstconfiguration, said plurality of radially extendible fingers assume acollapsed arrangement with said extending portions at least partiallycontained within said plurality of windows and substantially within saidperiphery, and in a second configuration, said plurality of radiallyextendible fingers assume an opened configuration with said extendingportions extending radially through said plurality of windows and beyondsaid periphery in a manner substantially perpendicular to saidlongitudinal axis.
 2. A surgical retention port according to claim 1,wherein: said distal end of said hollow inner cannula comprises a distalring coupled to a more proximal portion of said hollow inner cannula bya plurality of links which define a plurality of gaps, and said surgicalretention port further comprises a plurality of pins extending acrosssaid plurality of gaps from said distal ring to said more proximalportion, said plurality of pins extending through said pivot portions ofsaid radially extendible fingers such that said radially extendiblefingers rotate about pins.
 3. A surgical retention port according toclaim 2, wherein: each of said links includes a portion having athickness substantially equal to the thickness of said hollow innercannula.
 4. A surgical retention port according to claim 3, wherein:each of said links includes a second radially extending portion having athickness less than the thickness of said hollow inner cannula.
 5. Asurgical retention port according to claim 2, wherein: said distal ringhas a tapered thickness with a very distal end having a smaller outerdiameter than a proximal end of said distal ring.
 6. A surgicalretention port according to claim 5, wherein: said distal ring extendspast said distal end of said outer cannula.
 7. A surgical retention portaccording to claim 1, wherein: said outer cannula has a shaft portionhaving an outer periphery defining an oval with a first outer diameterand a second outer diameter.
 8. A surgical retention port according toclaim 7, further comprising: a locking collar extending about said shaftportion of said outer cannula, said locking collar defining an inneropening having an oval shape with a first inner diameter and a secondinner diameter, said first inner diameter being greater than said firstouter diameter and said second inner diameter being greater than saidsecond outer diameter, and said second inner diameter being smaller thansaid first outer diameter.
 9. A surgical retention port according toclaim 1, wherein: each said extending portion of said fingers has acurved surface defined by a radius equal to the radius of the outersurface of said outer cannula.
 10. A surgical retention port accordingto claim 1, wherein: said bars of said outer cannula include cammingsurfaces such that rotation of said inner cannula in a first rotationaldirection relative to said outer cannula causes said extending portionsof said fingers to engage said camming surface and to cause said fingersto move from said first configuration toward said second configuration.11. A surgical retention port according to claim 10, wherein: in saidsecond configuration said camming surfaces engage said pivot portions ofsaid fingers.
 12. A surgical retention port according to claim 11,wherein: said bars of said outer cannula include second surfacesrotationally remote from said camming surfaces such that rotation ofsaid inner cannula relative to said outer cannula in a second rotationaldirection opposite said first rotational direction said second surfacesto engage said extending portions of said fingers to cause said fingersto move from said second figuration toward said first configuration. 13.A surgical retention port according to claim 12, wherein: for anyparticular finger, a camming surface of a first of said bars engagessaid particular finger to cause said finger to move from said firstconfiguration toward said second configuration and a second surface of asecond of said bars engages said particular finger to cause said fingerto move from said second configuration toward said first configuration.14. A surgical retention port according to claim 1, wherein: said innercannula defines a groove about its outer surface between said distal endof said inner cannula and said second interface mechanism, and saidsurgical retention port further comprises an O-ring located in saidgroove and contacting an inner surface of said outer cannula.
 15. Asurgical retention port according to claim 14, wherein: adjacent saidgroove, said outer cannula has an oval inner surface and said innercannula has a circular outer surface.
 16. A surgical retention portaccording to claim 15, wherein: said groove in said inner cannula isoval such that it is deeper in certain locations and shallower in otherlocations.
 17. A surgical retention port according to claim 16, wherein:said inner cannula and said outer cannula are rotationally arranged suchthat deeper locations of said groove are adjacent a smaller diameter ofsaid oval inner surface of said outer cannula when said fingers assumesaid collapsed arrangement, and said shallower locations of said grooveare adjacent said smaller diameter of said oval inner surface of saidouter cannula when said fingers assume said open configuration.
 18. Asurgical retention port according to claim 1, wherein: one of said firstand second interface mechanisms is a longitudinally extending key and asecond of said first and second interface mechanisms is a keyway slot.19. A surgical retention port according to claim 1, further comprising:an elastomeric sleeve fixed to the distal end of said outer cannula andextending freely over said plurality of windows.
 20. A surgicalretention port according to claim 1, wherein: said outer cannula has aninwardly extending pin, and said inner cannula defines a locking slothaving a plurality of predetermined locking positions for said extendingpin.
 21. A method, comprising: a) obtaining a surgical retention port,comprising (i) a long pointed instrument having a shaft defining alongitudinal axis, a distal tip capable of dilating an incision, aproximal handle, and an first interface mechanism, (ii) a hollow innercannula extending about said long pointed instrument with said longpointed instrument movable longitudinally relative to said innercannula, said inner cannula having a distal end and a second interfacemechanism, said second interface mechanism for engaging with said firstinterface mechanism of said long pointed instrument such that rotationof said long pointed instrument causes rotation of said hollow innercannula, (iii) a plurality of radially extendible fingers coupled tosaid distal end of said hollow inner cannula, each of said radiallyextendible fingers having a pivot portion and an extending portion, and(iv) a hollow outer cannula having a proximal end, a distal end defininga periphery and a plurality of windows, said distal end including aplurality of bars between said windows, wherein in a firstconfiguration, said plurality of radially extendible fingers assume acollapsed arrangement with said extending portions at least partiallycontained within said plurality of windows and substantially within saidperiphery, and in a second configuration, said plurality of radiallyextendible fingers assume an opened configuration with said extendingportions extending radially through said plurality of windows and beyondsaid periphery in a manner substantially perpendicular to saidlongitudinal axis; b) with said fingers in said collapsed arrangement,pushing said surgical retention port into an incision of a patient suchthat said distal end of said inner cannula, said distal end of saidouter cannula, and said fingers are located inside the patient; c)rotating said long pointed instrument and thereby said inner cannularelative to said outer cannula to force said fingers into said extendedposition; d) removing said long pointed instrument from said innercannula; e) inserting a surgical instrument through said inner cannulaand manipulating the surgical instrument; f) removing the surgicalinstrument from said inner cannula; g) reinserting said long pointedinstrument into said inner cannula and rotating said long pointedinstrument to force said fingers back into said collapsed arrangement;and h) withdrawing said surgical retention port from the incision.
 22. Amethod according to claim 21, wherein said surgical retention portfurther includes a locking collar, further comprising: after saidrotating, sliding said locking collar over outer cannula until saidlocking collar engages the patient; and locking said locking collar inplace by rotating said locking collar relative to said outer cannula.23. A surgical retention port, comprising: a long pointed instrumenthaving a shaft defining a longitudinal axis, a distal tip capable ofdilating an incision, a proximal handle; a hollow inner cannulaextending about said long pointed instrument with said long pointedinstrument movable longitudinally relative to said inner cannula, saidinner cannula having a distal end, said distal end of said hollow innercannula comprises a distal ring coupled to a more proximal portion ofsaid hollow inner cannula by a plurality of links which define aplurality of gaps, and a plurality of pins extending across saidplurality of gaps from said distal ring to said more proximal portion; aplurality of radially extendible fingers coupled to said distal end ofsaid hollow inner cannula, each of said radially extendible fingershaving a pivot portion and an extending portion, said plurality of pinsextending through said pivot portions of said radially extendiblefingers such that said radially extendible fingers rotate about pins;and a hollow outer cannula having a proximal end, a distal end defininga periphery and a plurality of windows, said distal end including aplurality of bars between said windows, said hollow outer cannula andsaid hollow inner cannula being rotatably movable relative one to theother, wherein in a first configuration, said plurality of radiallyextendible fingers assume a collapsed arrangement with said extendingportions at least partially contained within said plurality of windowsand substantially within said periphery, and when said hollow innercannula is rotated relative to said hollow outer cannula from said firstconfiguration to a second configuration, said plurality of radiallyextendible fingers assume an opened configuration with said extendingportions extending radially through said plurality of windows and beyondsaid periphery in a manner substantially perpendicular to saidlongitudinal axis.
 24. A surgical retention port according to claim 23,wherein: each of said links includes a portion having a thicknesssubstantially equal to the thickness of said hollow inner cannula.
 25. Asurgical retention port according to claim 24, wherein: each of saidlinks includes a second radially extending portion having a thicknessless than the thickness of said hollow inner cannula.
 26. A surgicalretention port according to claim 23, wherein: said distal ring has atapered thickness with a very distal end having a smaller outer diameterthan a proximal end of said distal ring.
 27. A surgical retention portaccording to claim 26, wherein: said distal ring extends past saiddistal end of said outer cannula.
 28. A surgical retention portaccording to claim 23, wherein: said outer cannula has a shaft portionhaving an outer periphery defining an oval with a first outer diameterand a second outer diameter, and said surgical retention port furthercomprises a locking collar extending about said shaft portion of saidouter cannula, said locking collar defining an inner opening having anoval shape with a first inner diameter and a second inner diameter, saidfirst inner diameter being greater than said first outer diameter andsaid second inner diameter being greater than said second outerdiameter, and said second inner diameter being smaller than said firstouter diameter.
 29. A surgical retention port according to claim 23,wherein: each said extending portion of said fingers has a curvedsurface defined by a radius equal to the radius of the outer surface ofsaid outer cannula.
 30. A surgical retention port, comprising: a longpointed instrument having a shaft defining a longitudinal axis, a distaltip capable of dilating an incision, and a proximal handle; a hollowinner cannula extending about said long pointed instrument with saidlong pointed instrument movable longitudinally relative to said innercannula, said inner cannula having a distal end; a plurality of radiallyextendible fingers coupled to said distal end of said hollow innercannula, each of said radially extendible fingers having a pivot portionand an extending portion; and a hollow outer cannula having a proximalend, a distal end defining a periphery and a plurality of windows, saiddistal end including a plurality of bars between said windows, said barsof said outer cannula including camming surfaces, wherein in a firstconfiguration said plurality of radially extendible fingers assume acollapsed arrangement with said extending portions at least partiallycontained within said plurality of windows and substantially within saidperiphery, and upon rotation of said inner cannula relative to saidouter cannula in a first rotational direction, said camming surfacescause said plurality of radially extendible fingers to move from saidcollapsed position to a second open configuration with said extendingportions extending radially through said plurality of windows and beyondsaid periphery in a manner substantially perpendicular to saidlongitudinal axis.
 31. A surgical retention port according to claim 30,wherein: in said second configuration said camming surfaces engage saidpivot portions of said fingers.
 32. A surgical retention port accordingto claim 31, wherein: said bars of said outer cannula include secondsurfaces rotationally remote from said camming surfaces such thatrotation of said inner cannula relative to said outer cannula in asecond rotational direction opposite said first rotational directionsaid second surfaces to engage said extending portions of said fingersto cause said fingers to move from said second figuration toward saidfirst configuration.
 33. A surgical retention port according to claim32, wherein: for any particular finger, a camming surface of a first ofsaid bars engages said particular finger to cause said finger to movefrom said first configuration toward said second configuration and asecond surface of a second of said bars engages said particular fingerto cause said finger to move from said second configuration toward saidfirst configuration.
 34. A surgical retention port according to claim30, wherein: said inner cannula defines a groove about its outer surfacebetween said distal end of said inner cannula and said second interfacemechanism, and said surgical retention port further comprises an O-ringlocated in said groove and contacting an inner surface of said outercannula, adjacent said groove, said outer cannula has an oval innersurface and said inner cannula has a circular outer surface, and saidgroove in said inner cannula is oval such that it is deeper in certainlocations and shallower in other locations.
 35. A method, comprising: a)obtaining a surgical retention port, comprising (i) a long pointedinstrument having a shaft defining a longitudinal axis, a distal tipcapable of dilating an incision, and proximal handle, (ii) a hollowinner cannula extending about said long pointed instrument with saidlong pointed instrument movable longitudinally relative to said innercannula, said inner cannula having a distal end; (iii) a plurality ofradially extendible fingers coupled to said distal end of said hollowinner cannula, each of said radially extendible fingers having a pivotportion and an extending portion; and (iv) a hollow outer cannula havinga proximal end, a distal end defining a periphery and a plurality ofwindows, said distal end including a plurality of bars between saidwindows, said bars of said outer cannula including camming surfaces,wherein in a first configuration said plurality of radially extendiblefingers assume a collapsed arrangement with said extending portions atleast partially contained within said plurality of windows andsubstantially within said periphery, and upon rotation of said innercannula relative to said outer cannula in a first rotational direction,said camming surfaces cause said plurality of radially extendiblefingers to move from said collapsed position to a second openconfiguration with said extending portions extending radially throughsaid plurality of windows and beyond said periphery in a mannersubstantially perpendicular to said longitudinal axis; b) with saidfingers in said collapsed arrangement, pushing said surgical retentionport into an incision of a patient such that said distal end of saidinner cannula, said distal end of said outer cannula, and said fingersare located inside the patient; c) rotating said inner cannula relativeto said outer cannula in said first direction to force said fingers intosaid open configuration; d) removing said long pointed instrument fromsaid inner cannula; e) inserting a surgical instrument through saidinner cannula and manipulating the surgical instrument; f) removing thesurgical instrument from said inner cannula; g) rotating said innercannula relative to said outer cannula in a second direction oppositesaid first direction to force said fingers back into said collapsedarrangement; and h) withdrawing said surgical retention port from theincision.
 36. A method according to claim 35, wherein said surgicalretention port further includes a locking collar, further comprising:after said rotating, sliding said locking collar over outer cannulauntil said locking collar engages the patient; and locking said lockingcollar in place by rotating said locking collar relative to said outercannula.
 37. A method, comprising: a) obtaining a surgical retentionport, comprising (i) a long pointed instrument having a shaft defining alongitudinal axis, a distal tip capable of dilating an incision, andproximal handle, (ii) a hollow inner cannula extending about said longpointed instrument with said long pointed instrument movablelongitudinally relative to said inner cannula, said inner cannula havinga distal end, said distal end of said hollow inner cannula comprises adistal ring coupled to a more proximal portion of said hollow innercannula by a plurality of links which define a plurality of gaps, and aplurality of pins extending across said plurality of gaps from saiddistal ring to said more proximal portion (iii) a plurality of radiallyextendible fingers coupled to said distal end of said hollow innercannula, each of said radially extendible fingers having a pivot portionand an extending portion, said plurality of pins extending through saidpivot portions of said radially extendible fingers such that saidradially extendible fingers rotate about pins, and (iv) a hollow outercannula having a proximal end, a distal end defining a periphery and aplurality of windows, said distal end including a plurality of barsbetween said windows, wherein in a first configuration, said pluralityof radially extendible fingers assume a collapsed arrangement with saidextending portions at least partially contained within said plurality ofwindows and substantially within said periphery, and in a secondconfiguration, said plurality of radially extendible fingers assume anopened configuration with said extending portions extending radiallythrough said plurality of windows and beyond said periphery in a mannersubstantially perpendicular to said longitudinal axis; b) with saidfingers in said collapsed arrangement, pushing said surgical retentionport into an incision of a patient such that said distal end of saidinner cannula, said distal end of said outer cannula, and said fingersare located inside the patient; c) rotating said inner cannula relativeto said outer cannula in a first direction to force said fingers intosaid extended position; d) removing said long pointed instrument fromsaid inner cannula; e) inserting a surgical instrument through saidinner cannula and manipulating the surgical instrument; f) removing thesurgical instrument from said inner cannula; g) rotating said innercannula relative to said outer cannula in a second direction oppositesaid first direction to force said fingers back into said collapsedarrangement; and h) withdrawing said surgical retention port from theincision.
 38. A method according to claim 37, wherein said surgicalretention port further includes a locking collar, further comprising:after said rotating, sliding said locking collar over outer cannulauntil said locking collar engages the patient; and locking said lockingcollar in place by rotating said locking collar relative to said outercannula.